Selecting pitch of gears for a spur gear train 3

[agdyp]

I am designing a simple spur gear train. Goal is max output torque & high efficiency. OD of gears is pretty much fixed.

Could someone please suggest what would be the optimum pitch which I could consider? I am thinking 12 or 16 dp. However, I am not sure how much of a friction loss there will be with coarse pitch gears.

What are the other advantages and disadvantages of using coarse gears over fine pith gears other than noise?

Any feedback is highly appreciated.

Thank you.

Regards,
agdyp

 

[eromlignod]

There shouldn't be much friction loss. Coarse-pitch gears work by rolling contact, just like fine ones. Higher torque requires coarser pitch (bigger teeth). You'll have to size the gears based on your PD and your maximum torque requirements...anything finer will simply be undersized. If noise is a problem, you might consider helical or herringbone gears.

Don
Kansas City

 

[Javier72]

Be careful when choosing your dp. There is an optimus one. It is so bad to choose a tooth too small as to choose one too big.

If you are going to use coarse gears, the surface endurance is going to be reduced because your effective contact surface is going to be smaller. Problems as pitting appear before in coarse teeth than in finer ones (the engagement ratio is going to be smaller).

 

[dimjim]

Consider long and short addendum ie recess action gears to equalize and increase the strength of the pinions but also to increase their efficiency and life.

 

[Philrock]

Coarse pitch gears will have higher specific sliding than fine pitch gears of similar size. Higher specific sliding increases contact point temperature and contributes to increased surface wear. As a crude rule of thumb, the pinion should have 25 or more teeth to keep specific sliding at a reasonable level.

As the others have pointed out, the teeth must also be strong (large) enough to stand up to bending stresses.